Abstract
The Rollrock Section in the Sverdrup Basin, Arctic Canada, is one of the northernmost outcrops where the Jurassic-Cretaceous transition is accessible. The over 500 m thick sedimentary succession exposes the Oxfordian to Valanginian Ringnes and Deer Bay formations. Macrofauna from 15 discrete horizons includes ammonites, Buchia bivalves and belemnites. These fossils improve the biostratigraphy of the Tithonian and Berriasian in the Sverdrup Basin, provide correlation to the remainder of the Boreal Realm and set reliable calibration points. The occurrence of Buchia rugosa in the Ringnes Formation moves the upper formation boundary of from the top of the Kimmeridgian into the lower Tithonian. Dorsoplanites maximus and D. sachsi document the middle Tithonian Dorsoplanites maximus Zone in Arctic Canada for the first time. The late Tithonian to early Berriasian Buchia terebratuloides is considered to be the best approximate indicator of the Jurassic-Cretaceous transition in the Rollrock Section. The middle early Berriasian Praetollia maynci and the late early Berriasian Borealites fedorovi tie the respective horizons to the successive Chetaites sibiricus and Hectoroceras kochi zones. Two species of the belemnite Arctoteuthis, collected from an interval with glendonites, suggest a Valanginian age for the upper Deer Bay Formation. The dearth of Late Jurassic to earliest Cretaceous macrofossils in the Sverdrup Basin is inferred to be predominantly a function of diagenetic carbonate loss. Abundant dropstones and glendonites in the middle Tithonian to middle Valanginian interval suggest cold climatic conditions, and make the Rollrock Section a prime candidate for studying the Arctic environmental perturbations of this time.
| Original language | English |
|---|---|
| Article number | 104508 |
| Number of pages | 37 |
| Journal | Cretaceous Research |
| Volume | 114 |
| Early online date | 22 May 2020 |
| DOIs | |
| Publication status | Published - Oct 2020 |
Bibliographical note
Working in the Arctic would not be possible without manifold support. Our sincere thanks go to the following people in Canada who helped to make our research a success: Sylvie LeBlanc (Department of Culture and Heritage, Iglooik, Canada); Jane Chisholm (Parks Canada, Iqaluit, Canada); John Innis (Universal Helicopters); the rangers of Parks Canada at Quttinirpaaq National Park (Ellesmere Island, Canada); the Polar Continental Shelf Programme team at Resolute (Cornwallis Island, Canada); Margaret Currie, Laura Smyk and Kieran Sheperd (all Canadian Museum of Nature, Ottawa, Canada). Alex Chavanne (California, USA) joined our team as an excellent field assistant, helped logging and sampling the Rollrock Section and found the giant Dorsoplanites specimen. Sarah Wallace-Jones (Sedgwick Museum, Department of Earth Sciences, University of Cambridge, UK) provided access to preparation labs. Magdalena Biszczuk (CASP) prepared the maps in Fig. 1; and Michael Pointon (CASP) polished the English. Ashton F. Embry (Geological Survey of Canada, Calgary) kindly shared his field observations and analytical results on the Rollrock Section. Mikhail Rogov (Geologicheskij Institut, Rossijskaja Akademija Nauk, Moscow) greatly helped by sharing expert knowledge regarding ammonites of the Jurassic-Cretaceous boundary interval and by providing literature. CASP's industry sponsors are acknowledged for funding the Canadian Arctic Islands Project. Peter Alsen (Geological Survey of Denmark and Greenland, Copenhagen, Denmark) and Terence Poulton (Natural Resources Canada, Calgary, Canada) provided careful and detailed reviews, which greatly improved the manuscript.Keywords
- Tithonian
- Berriasian
- Valanginian
- palaeoclimate
- Buchia
- Dorsoplanitidae
- Craspeditinae
- belemnites
- Belemnites
- Palaeoclimate
- PATTERNS
- STRATIGRAPHY
- EVOLUTION
- SEEP
- SVERDRUP BASIN
- CLIMATE